Here is a simple way to observe the persistence for a perceptible length of time of every impression made upon the retina. Gaze fixedly for a minute or so at the black diamond in the center of the figure, and then turn your eyes quickly to a white wall or sheet of paper, and you will see the design in reverse, the figure black and the background white. The result is affected by the principle of complementary colors. A red design will be reproduced In green, orange in blue, yellow in violet, and vice versa.
[This post is based around an article included in the October 31, 1901 issue of The Country Gentleman (Volume LXVI, Issue 2544). Although as much effort as possible was put into preserving the article as it originally appeared, some aspects of the layout were impossible to replicate. To see the original, head on over to Google Books.]
